Original Article|Articles in Press

Class I Obesity Delays Achievement of Patient-Acceptable Symptom State but not Minimum Clinically Important Difference or Substantial Clinical Benefit After Primary Hip Arthroscopy for Femoroacetabular Impingement Syndrome

Published:February 19, 2023DOI:


      The aim of our study was to identify differences in the time taken to achieve the minimum clinically important difference (MCID), substantial clinical benefit (SCB), and patient-acceptable symptom state (PASS) following primary hip arthroscopy for the treatment of femoroacetabular impingement syndrome (FAIS) among patients of different body mass index (BMI) categories.


      We conducted a retrospective comparative study of hip arthroscopy patients with minimum 2-year follow-up. BMI categories were defined as normal (18.5 ≤ BMI < 25.0), overweight (25.0 ≤ BMI <30.0), or class I obese (30.0≤BMI<35.0). All subjects completed the modified Harris Hip Score (mHHS) prior to surgery and at 6 months, 1 year, and 2 years postoperative. MCID and SCB cutoffs were defined as pre-to-postoperative increases in mHHS by ≥8.2 and ≥19.8, respectively. PASS cutoff was set at postoperative mHHS ≥74. Time to achievement of each milestone was compared using the interval-censored EMICM algorithm. The effect of BMI was adjusted for age and sex using an interval-censored proportional hazards model.


      285 patients were included in the analysis: 150 (52.6%) normal BMI, 99 (34.7%) overweight, and 36 (12.6%) obese. Obese patients had lower mHHS at baseline (P = .006) and at 2-year follow-up (P = .008). There were no significant intergroup differences in time to achievement for MCID (P = .92) or SCB (P = .69), but obese patients had longer time to PASS than normal BMI patients (P = .047). Multivariable analysis found obesity to be predictive of longer time to PASS (HR = .55; P = .007) but not MCID (HR = 0.91; P = .68) or SCB (HR = 1.06; P = .30).


      Class I obesity is associated with delays in achieving a literature-defined PASS threshold after primary hip arthroscopy for FAIS. However, future research should consider incorporating PASS anchor questions to determine whether obesity truly carries a risk of delayed achievement of a satisfactory state of health as it pertains to the hip.

      Level of Evidence

      III, retrospective comparative study.
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